A set of bench-scale experiments were conducted to estimate the contribution of air
diffusion through water-filled pores to pressure decay in immersed membranes. The
apparatus consisted of a pressurized vessel, an air compressor, a pressure regulator and an
inverted water-filled burette for measuring the volume of diffused air.
The results obtained from air diffusion measurements allowed for consistent
determination of membrane's true bubble-point pressure and the size of the largest pore.
The results also indicated that air flowrate due to diffusion through an intact wetted
membrane is relatively constant for a specific membrane with the same surface area and
water temperature. Furthermore, it was demonstrated that the pressure decay in an intact
membrane was primarily due to air diffusion through water-filled pores. Therefore, the
dilution effect observed during pressure decay tests on membranes with large surface area
can be mainly attributed to air diffusion through intact pores.
Based on the experimental results a mathematical model was developed that estimates the
amount of air diffusion through an intact wetted membrane as a function of applied
pressure. The model also estimates the contribution of the diffusive airflow to pressure
decay test. It is proposed that subtracting this contribution from the measured pressure
decay tests can lead to more sensitive tests and better estimates of true log reduction values for microorganisms.
This paper presents the development and verification of the mathematical model for
estimating diffusion air flowrate through an intact ZeeWeed(R) 500 membrane.
Includes 8 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 260 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 03/05/2003 |
